What happened?The 300-foot South Korean warship Cheonan, carrying a crew of 104, sank in the Yellow Sea near North Korea on March 26 after an explosion ripped a hole in its hull. A team of more than 25 experts from South Korea, the U.S., Australia, Sweden, and Britain was dispatched to find out why and says the evidence points "overwhelmingly to the conclusion that [a] torpedo was fired by a North Korean submarine."

What's their evidence?The key discovery was a torpedo propeller that perfectly matches a model made in North Korea. The investigators also reported that a small group of submarines left a North Korean naval base a few days before the attack and returned a few days after.

Why would North Korea do this?One theory is that the alleged attack was retaliation for a naval scuffle between the two countries that left a North Korean ship in flames last November. There's also "the small chance that Kim Jong-il has descended into total madness," says The Guardian's Julian Borger. But the scenario "that should worry us the most is the possibility that it was not Kim Jong Il who gave the orders," says North Korea expert Ruediger Frank, since that would indicate destabilizing unrest brewing inside the Kim's government.

What happens next?South Korea in unlikely to respond militarily. Though "[North Korea] is very unlikely to court its own destruction by launching a nuclear attack," says Borger, "no responsible government in Seoul can bet on that." Instead, South Korea will almost certainly ask for tougher punitive sanctions from the United Nations Security Council. The wild card is Security Council member China, North Korea's "patron." The investigators "need to deliver their report very formally to China," says Kongdan Oh in The Atlantic, "and say look, if you want to be a great power in the 21st century, you are dealing with a gangster, and you should stop helping them. That is another form of sanction."